ABSTRACT The Annual Course on Principles of STI and HIV Research was first held in 1993 to provide an intensive overview of skills needed to pursue a research career in the field of STI/HIV. Since then, approximately 3,030 trainees have attended this annual course, including many women and racial/ethnic minority students. A broad, interdisciplinary approach provides early stage investigators with tools for continued learning, for collaboration in research teams, and for maintaining a broad scope of investigative possibilities. This course offers a unique opportunity for state-of-the-art introductory training in behavioral, clinical, epidemiologic, statistical, implementation, and basic science research by providing a practically oriented overview of language and skills common to these broad disciplines. Course duration is limited to two weeks to encourage individuals who are establishing active research careers and allow those who reside outside of the local area to attend. Course objectives are to: 1) Introduce early stage investigators to critical research areas and emerging questions in the field of STI/HIV; 2) Familiarize investigators with research techniques and tools needed to conduct scientifically and ethically sound studies, including study design, experimental approach, development of instruments for data collection, human subjects considerations, and data analysis; 3) Teach trainees the fundamentals of different disciplines involved in STI/HIV research in order to foster research collaborations; and 4) Discuss career development strategies, successful mentoring, competing for research funds, publishing one's work, and engaging in team science. The course integrates five tracks: 1) Essentials of STI/HIV interdisciplinary research; 2) Epidemiology, pathogenesis, and clinical aspects of specific infections; 3) Behavioral research methods and research in special populations; 4) Implementation science and health economics; and 5) Strategies for successful and ethical research. In addition to didactic instruction, students are engaged through a variety of active learning approaches, including grant workshops, journal clubs, and audience-response software. The course proceedings are disseminated on a participant website, which contains learning objectives, speakers' slides, audio recordings of lectures, and key references. The course is rigorously evaluated each year, and both participant feedback and discussions of the course Curriculum Committee inform annual updates and innovations to ensure the course is up-to-date, relevant, and employs active learning techniques. The 27th annual course has just concluded, and participant feedback remains extremely positive, demonstrating that the Principles of STI and HIV Research Course remains a critical resource for training the next generation of HIV and STI researchers.